The present invention relates to an electromagnetic actuator for activating an intake/exhaust valve in an internal combustion engine, with the activator having two spaced apart electromagnets, one of which is intended as an opening magnet for the generation of a magnetic force to open the intake/exhaust valve, and the other of which is intended as a closing magnet for the generation of a magnetic force to close the intake/exhaust valve, and also having an armature that can be moved by magnet force between opposing pole faces of the electromagnets and that is actively linked to the intake/exhaust valve.
An electromagnetic actuator of this type is described in the German patent DE 296 04 946 U1, for example. This known actuator features an opening magnet designed as an electromagnet, a closing magnet, which is also designed as an electromagnet and is arranged at a distance from the former, and an armature, which is actively linked to an intake/exhaust valve via a tappet. To open and close the intake/exhaust valve a magnetic force that acts upon the armature, causing it to move back and forth between two opposing pole faces on these electromagnets, is generated by alternately applying a current to the two electromagnets.
The major disadvantage of this actuator is that during the opening operation, when the armature is moved from the pole face of the closing magnet to the pole face of the opening magnet, in contrast to the closing operation, when the armature is moved from the pole face of the opening magnet to the pole face of the closing magnet, work has to be done to counteract the high internal gas pressure in the combustion chamber. The opening operation therefore takes longer than the closing operation, which has a negative effect on the dynamic properties of the actuator.